A Plasma-assisted fine particle classification method has been developed by using a positive column of glow-discharge in the Geisler tube. The particles are charged in plasma, in which their surface is covered with the sheath made of double layers of negative and positive ions. Charged particles fly to the positive electrode under high tension voltage. The flying mode, however, is influenced by the gravity and the collision of the plasma ions to the flying particles. A newlydeveloped classification setup is made with three main parts -the Geisler tube, a powder supplier and an evacuation system. The fine powders such as those of alumina, sillica and silicon carbide, were classified under the condition of DC voltage of 2kV and the tube current of 1.5mA at 1Torr. It was found from the experiments that the coaser particles fell down near the inlet of the powder supplier, but the finer ones flew apart from it. The classification characteristics may be determined by the charging mode and the electric property of particles.
